The long term objectives of this research are to determine the structure of mammalian alcohol dehydrogenase genes, and to examine the mechanisms which regulate their expression. These studies will contribute to our understanding of the factors underlying differences between individuals in the metabolic, pharmacological, pathological, and psychological effects of alcohol consumption. The genetic models of formation of alcohol dehydrogenase isozymes as products of different loci will be tested in both mouse and human. Complementary DNAs representing copies of the alcohol dehydrogenase messenger RNAs will be cloned from libraries of mouse and human liver cDNA. Isolation and nucleotide sequencing of different cDNAs for the different isozymes would prove the genetic models for formation of the isozymes and provide the amino acid sequences of each. If, after extensive searching, only one type of cDNA were found it would suggest the isozymes are differently modified forms of a single polypeptide; in that case the genome would be analyzed to determine whether there were only a single locus for the structural gene for alcohol dehydrogenase. The regulation of alcohol dehydrogenase isozyme content in different tissues and strains of inbred mice will be studied by measuring enzymatic activity, protein content, and alcohol dehydrogenase mRNA content. These studies will utilize portions of the cloned cDNAs as probes for measuring mRNA content. They should reveal whether there is a strong correlation between enzyme activity and mRNA content, and whether there are structural differences in the mRNA of different tissues. This will provide evidence for or against the model that alcohol dehydrogenase activity is regulated at the level of transcription. Finally, human alcohol dehydrogenase cDNAs isolated in the proposed study will be used to explore the possibility of determining the genotype of humans at the polymorphic ADH2 and ADH3 loci.